Illuminated manometer



Nav. 2,4, 1942. y v R HATNESS l 2,363,r21V

ILLUMINATED MANMET'ER Filed Nov. i7, 1941 ATTORN EYS Patented Nov. 24,1942 'UNITED' STATES PATENT -OFFICE C.

Application November 17, 1941, Serial No. '419,511

(Cl. 24o-2) 3 Claims.

This invention relates to manometers, particularly to the type employedfor ascertaining blood pressure in which a mercury column or equivalentuid body is pressure responsive to constitute the indicating element ofthe instrument, and has among its objects and advantages the provisionof novel illumination for such a device to render the pressure readingeasier, to facilitate reading in the country and homes where lightingconditions are not the best, and in sick rooms where strong lights arenot desirable. 'Ihe instrument is designed with a view to simplicity anddurability, and a small battery is electrically connected into theinstrument as a source of current supply, with an electric lampinterposed in the electric circuit and associated with the mercurycontaining tube in a novel manner to eiectively illuminate the latter tofacilitate reading of the scale.

In the accompanying drawing:

Figure 1 is an elevational view of a manometer in accordance with myinvention, with certain parts broken away for the purpose ofillustration;

Figure 2 is a top plan view; and Figure 3 is a sectional detail viewillustrating the manner in which the electric lamp is associated withthe mercury tube.

In the embodiment. selected to illustrate the invention, the glass tubeI0 is provided with the usual scale I2 etched in the glass, and thelower end of the tube is secured in a socket I4 formed on a fluidreservoir I6 which carries a supply of mercury I8. To the reservoir I6is connected a tube for connection with the customary ination facilitiesfor applying pressure to the mercury in the reservoir to force mercuryup into the tube I 0. The structure so far described is old and wellknown in the art and need not be set forth in greater detail.

Referring to Fig. 3, a metallic sleeve 22 is lnserted on to the upperend of the glass tube Ill, and a cap 24 has its tubular part 26 pressedon to the sleeve 22, the tubular part 26 being slotted at 28 andfashioned so as to resiliently press on to the sleeve. y

The threaded conducting sleeve 30 of the threevolt electric lamp |32 isthreaded into the bore 34 in the cap 24, and the central terminal 36 ofthe lamp 32 engages a terminal 38 carried by a body 40 of insulatingmaterial. To the outer end of the terminal 38 is secured a wire 42connected with one terminal of a three-volt battery 44, and the otherterminal of the battery is cona terminal 48 secured to the metallicreservoir I 6.

One end of a wire 50 is electrically connected with the sleeve 22 andthe other end is connected with a silverterminal 52 .extending throughthe wall of the glass tube to be engaged by mercury as it rises in thetube. Terminal 52 is preferably located at about the 25 mm. mark of thescale. To facilitate handling ofthe instrument, a switch 54 isinterposed in the wire 46 so as to positively break the circuit, as whenthe instrument is being carried in its case or the like.

When pressure is applied, as through the medium of the usual arm band,the mercury rises in the tube. When it reaches the 25 mm. mark, themercury makes contact with the terminal 52, which completes the circuitand the light is turned on. The light shines down the tube Ill and onthe mercury therein. The mercury in turn reflects the light thus makingthe manometer easy to read. When the mercury recedes beyond the 25 mm.point, the circuit is broken and the light is turned oif.

Without further elaboration, the foregoing will so fully illustrate myinvention that others may, by applying current knowledge, readily adaptthe same for use under various conditions of service.

I claim: Y

1. In a manometer, the combination of an upright transparent tube havinga scale thereon, a relatively opaque conducting liquid pressureresponsive to rise in the tube, an electric lamp located inside the tubeto illuminate the tube and liquid surface, an electric circuitelectrically connected with the lamp and said liquid, and a terminalinterposed in said electric circuit extending inside the tube to beengaged by said liquid when elevated a predetermined distance in thevtube to close the circuit.

2. In a manometer, the combination of an upright transparent tube havinga scale thereon, a relatively opaque conducting liquid pressureresponsive to rise in the tube, an electric lamp located inside the tubeto illuminate the tube and liquid surface, an electric circuitelectrically connected with the lamp and isaid liquid, a terminalinterposed in said electric circuit extending inside the tube to beengaged by said liquid when elevated a predetermined distance in thetube to close the circuit, and a switch interposed in said circuit tobreak the latter when said liquid is in contact with said terminal.

3. Ina manometer, the combination of an upright transparent tube havinga scale thereon, a relatively opaque conducting liquid pressure renectedwith a wire 46 electrically connected with 55 sponslve to rise in thetube, a conductor sleeve secured to the upper end of said tube, aconductor cap detachably engaging said sleeve, an electric lamp insidethe tube and having an outside terminal electrically connected with saidcap, said lamp being provided with a central terminal, a terminal postsupported on said cap but insulated therefrom and arranged to engagesaid central terminal, a battery, a connection between one terminal ofthe battery and said terminal post, a connection between the otherterminal of the battery and said liquid, a terminal carried by said tubeand extending therein above the normal level of the liquid, and aconnection between said last terminal and said sleeve, said lastterminal being engageable by said liquid when elevated a predetermineddistance in the tube to close the circuit through said lamp.

WILLIAM R. HARTNESS.

